1. Field of the Invention
The present invention relates to a roller bearing used in an internal combustion engine and an internal combustion engine using the same.
2. Background Art
In an internal combustion engine, for example, in a case where a camshaft is rotatably supported in a cylinder head, sliding bearings are generally used. In recent years, however, the actual situation is such that attention has been focused on less fuel-consuming internal combustion engines from the viewpoints of such as effective utilization of resources and reduction of carbon dioxides. Accordingly, attempts have been made to further reduce the power loss in internal combustion engines by changing sliding bearings to rolling bearings whose drag resistance is generally smaller (refer to JP-A-8-128306). In particular, in the so-called DOHC-type internal combustion engines and V-type internal combustion engines, the number of camshafts becomes relatively numerous in the light of their structures, so that it is expected that the change of the rolling bearings leads to some degree of improvement in fuel consumption.
Incidentally, a pair of cam lobes are generally formed in each cylinder, and journal portions which are supported by rolling bearings are disposed between the cam lobes or between the cam lobe and a large-diameter end portion. Therefore, there is a problem in that ordinary rolling bearings cannot be fitted on the journal portions by passing the cam lobes and the like which project more radially outward. Accordingly, it has been conceived to circumferentially split retainers of rolling bearings and to build these split retainers onto the journal portions from the radially outer side without passing the cam lobes and the like, in the same way as conventionally used sliding bearings (refer to JP-A-2001-12214).